Polycystic kidney disease will be induced in rats and rabbits by the use of a variety of chemical compounds. The disease produced by these substances has been previously shown to be similar to human forms of cystic disease of the kidney. An attempt will be made to determine what diagnostic parameters will allow the earliest recognition of the presence of functional renal abnormalities. The defect in urine concentrating capacity known to occur in patients with polycystic kidney disease is expected to develop in some of the animals, and the mechanisms of this derangement will be studied. Renal metabolism will be studied in tissue slices, isolated nephrons and renal mitochondria obtained from the diseased kidney. The capacity of the diseased kidney to respond to hormones such as antidiuretic hormone and parathyroid hormone will be assessed. Renal transport of electrolytes, organic acids and phosphate will be studied. The capacity of the kidney to reabsorb glucose and its ability to handle bicarbonate will be determined. The possible role of Na plus, K plus-ATPase in this disease process will be investigated. Clearance techniques and micropuncture will be utilized to obtain most of the physiological data sought.